Modernize Retrier to work in an async environment

[tusmester]

• [ ] make sure that every part of the Retrier api is async, including the action and the delay inside
• [x] modernize the API (method and parameter names) to be more developer-friendly
• ~replace the old Retrier in the sensenet repository with this~

[tusmester]

Issue moved to SenseNet/sn-tools #64 via Zenhub